Centrifugal switch assemblies



July 6, I965 E. B. ANGOLD CENTRIFUGAL SWITCH ASSEMBLIES 3 Sheets-Sheet 1 Filed Dec. 6, 1960 CEN'I'RIFUGAL SWITCH ASSEMBLIES Filed Dec. 6, 1960 5 Sheets-Sheet 2 Fig.4.

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y 1965 E. B. 'ANGOLD 3,193,639

CENTRIFUGAL swmm ASSEMBLIES Filed Dec. 6. 1960 3 Sheets-Sheet 5 3,193,639 CENTRHFUGAL SWHTCH ASSEMBLIES Edward Barnabas Angold, Shcnfield, Engiand, assignor to The Plessey Company Limited, London, England, a British company 7 Fiied Dec. 6, 1960, Ser. No. 75,956 4 Claims. ((31. 200-80) This invention relates to switch assemblies and is more particularly, but not exclusively, concerned with a centrifugally operated switch.

Broadly, in accordance with the present invention there is provided a centrifugal switch assembly including a centrifugal switch rotor wherein the rotor has a frame which is adapted pivotally to support the governor weights, i.e. of the switch rotor and wherein each weight is provided with at least two lugs which face towards the lugs on the other weight, the lugs being adapted to act as locating means for compression springs which carry a switch contact actuating element of the rotor.

In accordance with a second aspect of the invention two spaced leaf springs each having one end thereof attached to an insulating base board, the other ends of the springs being interconnected by a bridging member which bears upon an edge of the base board which edge acts as 'a pivot for the member, and wherein the two springs and the bridging member are so arranged that during switch actuation the bridging member pivots about said edge for a predetermined portion of switch actuation after which the bridging element is moved bodily out of contact with the board. Preferably the bridging element rocks about the contacts.

For a better understanding of the invention one constructional arrangement of a switch assembly will be described in greater detail in relation to the accompanying drawing in which:

FIGURE 1 is a plan view of a spring-loaded switch assembly,

FIGURE 2 isa schematic section of the assembly in FIGURE 1 illustrating the shaping of the spring used on the assembly, 7

FIGURE 3 is a perspective view of the switch rotor assembly, I

FIGURE 4 is a section on the line IV-IV of FIGURE 3, the FIGURE 4 also illustrating the setting of the switch in both of its operative positions,

FIGURE 5 is an elevation of the switch shown in FIGURES 3 and 4, and

FIGURE 6 is a further elevation of a switch rotor assembly shown in FIGURES 3 to 5 in its positional relationship in respect to the contact assembly shown in FIGURES l and 2.

The switching contact assembly includes a base board 1 having a relatively large substantially rectangular recess 2 cut'out along one edge 3 thereof. Two spaced leaf spring elements 4 and 5 are each attached at one end 6 and 7 respectively to the base board so that the other ends 8 and 9 thereof overhang the edge 19 of the cutout portion 2. The leaf springs are deformed or kinked as at 1%) intermediate of the ends thereof so that the ends 8 and 9 project beneath the upper surface of the base board. Electrically insulating elements 11 and 12 are attached to the ends 8 and 9 respectively, thus providing a contacts actuating structure. The ends 8 and 9 of the leaf springs 4 and 5 are bridged by a V-shaped metallic springable contact carrying member 13 which is so attached to the leaf springs 4 and 5 that the apex 14 of the V is located between the leaf-springs 4 and 5 and above the upper surface of the base board. The ends of the arms 15 of the member 13 are attached to the ends 3 and 9 of the leaf springs t and 5. The apex 14 of the 3,193,539 Patented July 6, 1965 ice Vis extended in the opposite direction of the arms of the V to form a support 16 for an electrical contact 17, which is co-oper-able with a contact 18 provided on the base board 1. Each arm 15 of the member 13 bears upon the forward edge 19 of the cut-out portion in the base board 1 so that the forward edge acts as a pivotal axis for the contact carrying member 13. Each arm 15 is kinked as at 15A.

The operation of the contact device described above is as follows:

When the contacts are in the rest position, i.e., the position shown in FIGURE 2 in which the contacts 17 and 13 are open and the arms 15 of the V-shaped member rest upon the edge 19 of the base board 1, the contacts are closed by moving the insulated elements 11, 12 against the resilient loading of the leaf springs 4 and 5. During the first part of this movement the leaf springs 4 and 5 accommodate the movement of the elements 11 and 12 and in so doing the arms of the vc-shaped element pivot about the forward edge 19 of the base board. This pivotal motion about the edge 19 of the base board continues until the contacts make after which the leaf springs 4 and 5 are causedbodily to move with respectto their fixed ends 6 and 7 owing to the pressure exerted on the insulating contact elements.

Referring now to the FIGURES 3 to 6 of the accompanying drawings the centrifugal switch rotor includes a switch frame 20 having a generally rectangular outline with two pointed arms 21 which are deformed so as to provide two members directed at an angle to the general plane of the frame 20. A central flange 22 is formed integrally with the frame 20, the flange 22 acting as a boss which is intended to engage as a force fit upon a shaft 23 shown in FIGURE 6. The flange 22 projects from the frame 26 in a direction opposite to the wings 21.

A switch contact operating member or element 24 having an annular switch contact abutment surface 25 which is integrally connected with two rearwardly directed arms 26 and 27, each arm 26 or 27 terminating in two transversely, inwardly directed limit stops 28 is loosely mounted on the frame 2%) so that the annular contact surface 25 is substantially coaxial with the boss 22. Each arm 26 or 27 is provided with a tapering claw member comprising a curved pointed finger 29 which is so curved as to overlie the outer surface of the associated arm 26 or 27 with the point of the finger 29 pointing towards the associated arm 26 or 27.

The pointed finger elements 29 are intended to engage in between two of the coils of compression springs 39 and 31 which are located between the rear face of the annular contacting surface 25 and the outer surfaces of the arms 26 and 27 so that the springs 30 and 31 are effectively held against the surfaces of the arms 26 and 27.

The frame 20 has two rectangular cut-outs 32 and 33 whose longer sides 34A, 34B extend perpendicularly to the longer edges of the rectangular portion of the frame 20. The outermost longer edges 34B serve as pivot surfaces for the governor weights 35 of the switch. Each governor weight 35 comprises a plate 36 to which a relatively heavy block 37 is attached. A finger 38, which extends perpendicularly to the plane of the plate, is provided at each end of each one of the plates. The fingers 38 being intended to engage in the open ends of the compression spring 30 and 31.

In addition the plate is provided with a U-shaped hook portion 39 which engages with the outer longer edge 34B of the associated cut-out 32 and 33 in the main frame 20. The shaping of the frame 20 is such that the springs 3t) and 31 are slightly normally deformed out of their straight condition in such manner that the switch actuating element 24 is moved to such a position that, the lugs 1* V a JD 28 bear against one of the surfaces of the frame 20. In addition the arms 21 act as limit stops for the weights 37. By deforming the arms 21 relative to the plane of the frame 20 the amount of angular movement and thus the governing characteristics of the weights 37 can be varied. In this position, which is shown in FIGURE 3 and in the full lines of FIGURE 4, the blocks 37 do not contact with the arms 21. The position shown is the normal rest position of the switch contacting element 24 with respect to the frame 20.

The above described rotor assembly can be assembled without the use of screwed or soldered joints. During the assembly of the rotor the springs 30 and 31 are positioned on the arms 26 and 27 respectively so that the pointed finger elements 29 engage in the centre part of the springs, and the fingers 38 are engaged in the respective ends of the springs 30 and 31. After the fingers 38 are positioned in the ends of the compression springs 30 and 31 the plates 36 are pressed towards each other in order to allow the hook elements 39 to engage with the aforesaid outer longer edges 34B of the cut-outs 32 and 33. The engagement of the hook elements 39 with the frame 20 is maintained by the stored energy of the compression springs 31 and 32 and in addition by reason of the relative dimensioning of the switch contact actuating element 24 and the frame 20. The springs 30 and 31 are normally curved out of a straight line in a direction away from the annular contact surface 25.

When the shaft 23 upon which the switch rotor is mounted is rotated the centrifugal force tends to move the weights 37 about their pivoting axis in such direction as to move the switch actuating plate surface 25 towards the main frame 20, that is into the position in which the frame 20 abuts the forward ends of the arms 26 and 27. This position is shown in chain-dotted lines in FIGURE 4.

The speed at which a switch contact operating element 24 moves relative to the frame 20 is dependent upon the angle of the arms 21 relative to the remainder of the frame 20, the angle at which the plate 36 is positioned to the frame 20 (this angle as mentioned above can be variedby adjusting the angle of the arms 21 with respect to the body or the remainder of the frame), the weight and compression of the spring.

The speed at which the contact operating element 24 moves in the release direction, i.e., from the position shown in chain'dotted lines in FIGURE 4 to the position in full lines in FIGURE 4, is dependent upon the amount of possible travel of the operating element.

The action of the switch rotor movement is positive by reason of the stored energy of the springs 30 and effectively provides a snap acting switch in both directions.

Referring particularly now to FIGURES and 6, the relative positioning of the contact assembly relative to the switch contact operating element 24 is illustrated. The positioning is such that when the motor is at rest the contact elements 12 are in contact with the surface 25. In this condition the switch contacts are held in their contact-made position by means of the switch contact operating element 24. When the motor is running and the speed reaches the release speed of the switch the surface 25 is retracted completely free of the switch thereby allowing the contacts 17 and 18 to open. The contact assembly shown in FIGURE 6 includes contact connectors 40 and 41.

What I claim is:

1. A centrifugally-operated switch responsive to the speed of rotation of a rotary member, comprising:

(a) a frame adapted to be secured to the rotating member,

(b) at least two weighted governor arms provided with means including outwardly-directed bearing surfaces engaging corresponding bearing surfaces on the frame for pivotal movement of the arms relative to the frame, 7

(c) at least one compression spring means, means connecting the ends of said spring means to each of the governor arms, said last named means respectively positioned on opposite sides of a plane of the axis of rotation and retaining the governor arms in a pivotal position with their bearing surfaces engaged with those of the frame, said spring means flexed to bias the governor arms in a pivotal position generally towards the axis of rotation,

(d) an axially movable switch operating member secured to an intermediate part of the spring means, whereby pivotal movement of the governor arms in response to centrifugal forces causes axial movement of the switch operating member which is supported solely by the said spring means,

(e) a plurality of co-operating electrical contacts, and,

(f) a contacts actuating structure mechanically connected to at least one of said contacts and including a contacts actuating engagement surface engageable by said switch operating member for operating said contacts.

2. A device as set forth in claim 1, wherein said compression spring means are situated on opposite sides of the axis of rotation, and wherein the switch operating member is secured to said spring means at the mid-points thereof.

3. A device as set forth in claim 2, wherein the said compression spring means are coil springs with their ends fitting over inwardly-directed projections on the respective governor arms.

4. A device as set forth in claim 3, wherein the switch operating member is secured to the said springs by two tapering claw members each of which partly embraces a spring and at its tip enters between two adjacent turns thereof.

References Cited by the Examiner UNITED STATES PATENTS 2,514,114 7/50 Aben 200- 2,631,025 3/53 Bone 200-80 2,757,253 7/56 Gaubatz 200-80 2,797,080 6/57 Johnson 200-80 3,076,874 2/ 63 Aquillon.

BERNARD A. GILHEANY, Primary Examiner. MAX L. LEVY, Ea qminer, 

1. AN CENTRIFUGALLY-OPERATED SWITCH RESPONSIVE TO THE SPEED OF ROTATION OF A ROTARY MEMBER, COMPRISING: (A) A FRAME ADAPTED TO BE SECURED TO THE ROTATING MEMBER, (B) AT LEAST TWO WEIGHTED GOVERNOR ARMS PROVIDED WITH MEANS INCLUDING OUTWARDLY-DIRECTED BEARING SURFACES ENGAGING CORRESPONDING BEARING SURFACES ON THE FRAME FOR PIVOTAL MOVEMENT OF THE ARMS RELATIVE TO THE FRAME, (C) AT LEAST ONE COMPRESSION SPRING MEANS, MEANS CONNECTING THE ENDS OF SAID SPRING MEANS TO EACH OF THE GOVERNOR ARMS, SAID LAST NAMED MEANS RESPECTIVELY POSITIONED ON OPPOSITE SIDES OF A PLANE OF THE AXIS OF ROTATION AND RETAINING THE GOVERNOR ARMS IN A PIVOTAL POSITION WITH THEIR BEARING SURFACES ENGAGED WITH THOSE OF THE FRAME, SAID SPRING MEANS FLEXED TO BIAS THE GOVERNOR ARMS IN A PIVOTAL POSITION GENERALLY TOWARDS THE AXIS OF ROTATION, (D) AN AXIALLY MOVABLE SWITCH OPERATING MEMBER SECURED TO AN INTERMEDIATE PART OF THE SPRING MEANS, WHEREBY PIVOTAL MOVEMENT OF THE GOVERNOR ARMS IN RESPONSE TO CENTRIFUGAL FORCES CAUSES AXIAL MOVEMENT OF THE SWITCH OPERATING MEMBER WHICH IS SUPPORTED SOLELY BY THE SAID SPRING MEANS, (E) A PLURALITY OF CO-OPERATING ELECTRICAL CONTACTS, AND, (F) A CONTACTS ACTUATING STRUCTURE MECHANICALLY CONNECTED TO AT LEAST ONE OF SAID CONTACTS AND INCLUDING A CONTACTS ACTUATING ENGAGEMENT SURFACE ENGAGEABLE BY SAID SWITCH OPERATING MEMBER FOR OPERATING SAID CONTACTS. 